The theoretical seismic reflection response of sedimentary sequences

A sedimentary sequence can quite often be considered very fruitfully as a discrete Markov chain, and thus can be described by a stochastic matrix. Knowing this matrix and the thickness probability distributions of the layers of the various participating lithologies, while assuming that their densities and velocities are normally distributed, an expression is derived for the autocorrelation (or power spectrum) of the seismic reflection response. This expression can bring out essential characteristics of the power spectra, i.e., the low‐frequency droop and its slope. This then leads to the possible estimation of some physical and sedimentary parameters of the sequence such as the scatter of the reflection coefficients and the sand‐shale ratio or sedimentary cycle thickness. The case of a binary sequence, as the predominant sequence of the sediments of the Gulf Coast area and Nigeria, is analyzed in detail. The theoretical results conform well with field data and lead to the interesting conclusion that indeed the estimation of the above mentioned parameters is possible.